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https://github.com/k-bx/par
Small utility that runs multiple computations in parallel
https://github.com/k-bx/par
haskell parallel scripting shell
Last synced: 13 days ago
JSON representation
Small utility that runs multiple computations in parallel
- Host: GitHub
- URL: https://github.com/k-bx/par
- Owner: k-bx
- License: mit
- Created: 2015-04-08T11:41:38.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2020-04-25T20:30:07.000Z (over 4 years ago)
- Last Synced: 2024-10-04T15:44:02.770Z (about 1 month ago)
- Topics: haskell, parallel, scripting, shell
- Language: Haskell
- Homepage:
- Size: 38.1 KB
- Stars: 41
- Watchers: 5
- Forks: 5
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# [](https://travis-ci.org/k-bx/par) Run several commands in parallel
`par` is a small utility that runs multiple commands in parallel and
by default exits with a failure status of a first failure it sees.
Use `--help` for command-line help.
Basic usage example
-------------------
```
> par "echo foo; sleep 1; echo foo; sleep 1; echo foo" "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
foo
bar
bar
foo
bar
foo
success
> par "echo foo; sleep 1; foofoo" "echo bar; sleep 1; echo bar; sleep 1; echo bar" && echo "success"
bar
foo
bar
/bin/sh: foofoo: command not found
bar
```
Passing commands over stdin
---------------------------
Plot 6 streams of data in real time with [feedgnuplot](https://github.com/dkogan/feedgnuplot):
```
for n in a b c d e f; do echo PARPREFIX=$n' (while true; do echo $RANDOM; sleep 0.2; done)'; done | par | feedgnuplot --dataid --stream 0.2 --xlen 1000 --lines --points --terminal qt --exit --autolegend
```
Adding prefix to output
-----------------------
```
> par "PARPREFIX=[fooechoer] echo foo" "PARPREFIX=[bar] echo bar"
[fooechoer] foo
[bar] bar
```
Force success exit-code
-----------------------
```
> par --succeed "foo" "bar" && echo 'wow'
/bin/sh: foo: command not found
/bin/sh: bar: command not found
wow
```
Forcing processes to not buffer their output
--------------------------------------------
Prefix your subprocesses with this command:
```
stdbuf -o 0
```
Installation
------------
For Ubuntu 12.04, 14.04 and MacOS X download some release and put it
into $PATH. For others -- see "building from source" instructions.
https://github.com/k-bx/par/releases
Example:
```
cd /tmp
wget https://github.com/k-bx/par/releases/download/1.0.1/par-ubuntu-12.04
sudo mv ./par-ubuntu-12.04 /usr/local/bin/
```
Building from source
--------------------
1. Install [haskell stack tool](https://github.com/commercialhaskell/stack)
2. Run `stack install`. It'll build and install tool into `~/.local/bin/par`
Footnote on strings in bash/zsh
-------------------------------
Many people know that strings in bash and zsh are "weird", but not
many people know that there are good old ASCII-strings also present.
Double-quoted strings are interpolating variables and do other interesting
things like reacting on "!" sign, for example.
Single-quotes don't interpolate variables and don't react on "!" sign, but
they also don't let you quote neither single-quote nor double-quote.
Turns out good old ASCII-quotes are available as $'string' syntax! Example:
> echo $'foo'
foo
> echo $'foo with "doublequotes and \'singletuoes\' inside"!'
foo with "doublequotes and 'singletuoes' inside"!
You are a better person with this knowledge now. $'Enjoy!'
Par-like thing in pure Bash
---------------------------
```
prefixwith() {
local prefix="$1"
shift
stdbuf -o 0 "$@" 1> >(sed "s/^/$prefix: /") 2> >(sed "s/^/$prefix (err): /" >&2)
}
listenqueue() {
local queue="$1"
prefixwith "[$queue]" kafkacat -b localhost -t $queue -o end &
}
listenqueue diarizer-input
P01=$!
listenqueue diarizer-output
P02=$!
wait $P01 $P02
```
But this has problems with stopping (need to re-create TTY).